Marine power transmission



Aug. 31, 1937. D. H. MONTGOMERY MARINE POWER TRAN SMI S S ION s sheets-sheet 1.

Filed April 9,v 1935 INVENTOR omlld/lfwzgomey BY ATTORN EYS Aug- 31 1937- *l D. H. MoNTGoMl-:RY 2,091,557V l MARINE 'POWER TRANSMIssI'oN .Filed April 9, 1935 s Sheets-Sheet 2 .m/1W INVENTOR ld lIMonfgamery ATTORNEYS Aug. 31, 1937. D. H. MONTGOMERY MARINE POWER TRANSMISSION s sheets-'sheet s Filed April 9, 1935 lNvENToR Darzaldjontgumery ATTORNEYS Patented Aug. 31, 1937 PA'rrzN'r orrics 2,091,551 i MARINE POWER TRANSMISSION Donald H. Montgomery, Berlin, Conn., assignor to Montgomery and Fleming, Incorporated, Hartford, Conn., a corporation of Connecticut Application April 9, 1935, Serial No. 15,501

7 Claims. (Cl. lim-3.5)

. ble engine.

Heretofore it has been the general marine practice to provide a special marine engine together with a reverse gear unit, and in the case of high speed engines with a separate reducing gear unit.

10 Attempts have been made to adapt modern high speed automotive types'of engine to marine use, but the adaptation of such engines has entailed extensive conversion costs so that the net result has been in general no more .satisfactory than when a standard marine engine was employed.

For marine use there are very substantial advantages in a high speed modern automotive type of engine, among the advantages being low first cost, lightness, compactness, and the'ready availability of repair parts in nearly all parts of the country.

It is a general object of my invention, therefore, to provide simple, inexpensive, and efficient means for adapting high speed automotive or industrial type engines to marine use.

It is a more specic object to provide a cornbined reverse and reducing gear, which is simple in construction, relatively cheap to manufacture, and in general of higher efliciency, than the combined efficiency of the separate reverse and reducing gears heretofore employed.

`It is another object to provide an outboard reverse and reducing gear combined in a single unit and which will have substantially equal efficiency in both forward and reverse.

It is another object to provide a marine gear having provision for horizontal mounting of the engine regardless of the slant or angularity of the propeller shaft.

It is a further object to provide a reverse gear of the positive or tooth clutch type and having means for initiating the drive frictionally.

It is another object to provide an improved means to facilitate gear shifting.

Other objects and various features of invention will be hereinafter pointed out or will become apparent to one'skilled in the art.

In the drawings which show, fory illustrative purposes only, preferred forms of the invention- Fig. 1 is a sectional View of the stern of a boat and an automotive engine and an outboard gear illustrating features of the invention;

Fig..2 is an enlarged sectional view through a part of the outboard gearing shown in Fig. 1;

Fig. 3 isa central sectional view through an inboard reverse and reducing gear unit illustrating features of the invention; Fig. 4 is an enlarged fragmentary end view of the right-hand or forward drive gear shown in Fig. 3;

Fig, 5 is an enlarged fragmentary end view of the clutch shown in Fig. 3 looking toward the left; Fig. 6 is a sectional view of a reverse gear and clutch, illustrating improved means to facilitate 10 gear shifting;

Fig. 'l is a sectional view taken substantially in the plane of the line 1-1 of Fig. 6.

In the drawings, and referring particularly to Figs. l and 2, 5 indicates generally a boat having 15 a transom 6. The engine 1 is preferably mounted directly in the stern of the boat and may be mounted substantially horizontally as in automotive practice. The engine illustrated is ofthe high speed, high production type 'Which is quite 20 inexpensive and readily available in all parts of the country. Between the engine I and the transom is the usual clutch housing 8 housing a suitable disk or other type of friction clutch usually employed in automotive practice. lThe clutch is 25 actuated through the clutch shift leverS in any suitable manner not disclosed.

The drive shaft Il) passes through the clutch housing and is journaled in a double row bearing II in a sleeve l2 extending from the outboard 30 forward and reverse gear housing I3. The sleeve I2 may extendthrough an aperture in the transom and is suitably sealed therein and held in position when the main housing I3 is bolted or otherwise firmly secured to the transom` The 35 shaft I0, extending toward the left in Fig. 2, is rotatably mounted in a quill or sleeve I4 which carries a forward driving bevel pinion I5 rigid therewith. The quill is rotatablysupported in a sleeve I6 held within the sleeve I2, and in the 40 form shown spaced pre-loaded ball bearings l1-I8 serve to rotatably support the quill I 4 both radially and axially. The shaft I0 extends farther to the left and at its extreme end is mounted in a double row bearing I9 floating in a recess 20 45 in the forward end of a reverse drive quill 2| which is itself rotatably supported both axially and radially by spaced apart pre-loaded bearings 22.' The quill 2l carries the reverse bevel drive pinion 23 rigidly mounted thereon.

The quill I4 is provided with a frictionclutch face 24 and positive clutch elements such as teeth 25. The reverse drive quill 2| is provided -wlth a similar friction clutch face 26 and similar positive clutch teeth 21. The shaftY I0 near its end is provided with splines 28 and a shiftable boss 29 is splined thereon for back and forth movement, as will be described. 'I'he splined boss is provided at opposite sides with friction clutch g faces 30-3I for coa'ction with the adjacent friction clutch faces 24-26 on the respective drive quills. Apositive clutch sleeve 32 is splined on the boss 29 and is provided internally with positive clutch teeth 33 for coacton with either the teeth 25 or the teeth 21 .depending upon the position of the positive clutch sleeve 32. The clutch sleeve 32 may be shifted back and forth by a fork 34 which is actuated in any suitable manner (not shown). sleeve 32 is splined to and slidable longitudinally of the shaft on the boss 29, the sleeve and boss are at times held in fixed position relatively to each other by releasable means such as a spring pressed ball 35 carried by the boss 29 and taking into a groove or depression 36 in the sleeve 32.

The teeth 33 may be termed shiftable teeth. the teeth 25 as forward drive teeth, the teeth 21 as "reverse drive teeth, and either teeth 25 or 21 as selected teeth (selected for engagement by teeth 33). All of these teeth in effect constitute two `positive tooth clutches, but for convenience are referred to as the forward and reverse gear clutch, positive clutch or double-actingtooth clutch or are identified .collectively by similar language. 'I'he pairs of complementary friction faces 24-30, 26-3I are referred to as friction clutch means, friction pick-up devices or are similarly identified. 'Ihese terms are intended to apply to corresponding parts in Figs. 3 to '1 inclusive.

'Ihe forward and reverse bevel gears I5-23 are in mesh with a bevel gear 40 xedly carried on a shaft 4| which extends downwardly in the housing. The' shaft 4I is geared to the propeller shaft 42 for driving the same as bymeansof bevel gears 43. 'I'he shaft 4| is mounted top and bottom in bearings within the housing I3 which bearings may be 'in the form of double row ball bearings as indicated at 44 at the top of the shaft.

which, as stated, may be bolted directly to the transom of the boat. The housing I3 may carry an ample supply of lubricant which -is cooled by the water surrounding the housing. Positive lubricating means may be provided, if desired, for

- be turning. The mst effect of shifting' the clutch fork 34 will be to carry the sleeve 32, and through the -releasable connection 35-36 the boss. 29, toward the right so; as to engage the friction faces 24-30 and thus cause the quill I4 and splined boss 29 an'd positive clutch sleeve 32 to rotate at substantially the same speed or at speeds sufficiently close together to permit a ready engagement of the positive clutch teeth 25 and 33. This latter engagement is eected by a further shift of the sleeve 32`tow'ard the right which.

forces the ball 35 radially inwardly and out of its groove'or notch 36 so as to permit the engage- While the positive clutch` All of the gearing described is mounted v within and carried by the single housing I3.-

ment of the positive clutch teeth noted. The main clutch 8 may then be engaged and the propeller will be driven by the engine positively in the 'forward direction. IWhen it is desired to reverse, the main clutch 9 is preferably thrown out and the clutch shift fork 34 is then moved toward the left. The boat will at this time be moving forward and the propeller will continue to turn, rotating clutch teeth 21 in a direction opposite to that of teeth 33. Such movement of fork 34 rst disengages the positive or forward drive clutch teeth 25-33 and againfbrings the groove- 36 oppositethe ball 35 to thus releasably hold the clutch sleeve 32 and splined boss *29 in engagement with each other. A further movement to the left causes engagement of the oppositely rotating friction fraces 26-3I which rst reverses the direction of rotation of boss 29, shaft I0 and teeth 33 and then causes the shaft I0 and sleeve 2| to be brought up to substantially the same speed, or to speeds near e'nough to each other, whereby the positive clutch teeth 21-33 may be engaged upon a further shift of the sleeve 32 toward the left, as heretofore described. The boat usually is still moving forward and hence shaft I0 is rotating oppositely to the crank shaft (not shown) of the engine. The main clutch Il is again engaged to initiate and effect reverse rotation of shaft I0 and the propeller shaft will then be driven in reverse direction by the' shaft I0 clutched to the crank shaft.

Heretofore, so far as I am advised, it has been entirely impracticable to employ a simple form of double-acting tooth or bump reversing clutch to drive the propeller shaft alternately in forward or reverse directions because in reversing the 1 propeller from full speed ahead to full speed astern, as often is necessary in an emergency, the linear speed limit of engagement of the oppositely rotating clutch teeth is materially exceeded. resulting in damage to the clutch, or such a loss 'of time as to involve the boat in' a collision, or both. Therefore employment of the simple double-acting tooth clutch (alone) is virtually impossible in the use of the reduction 'gearing disclosed herein, because the propeller over-drives both the teeth 25 and the teeth 21, so that the speed limit of engagement of the shiftable teeth 33 therewith is materially exceeded.

By means of the present improved construction such positive clutch means for forward and reverse have proven entirely practicable for the reason that one of the oppositely rotating positive clutch parts is rst reversed in direction of rotation and the parts caused to rotatein the same direction and then are brought up' tothe same speed or to speeds sufficiently close together to permit ready 4engagement; of the positive clutch teeth without damage. This can be accomplished very quickly because the disengagement of the main clutch leaves the relatively light drive shaft and parts carried thereby free for the described operation. Therefore, as has been repeatedly proved in practice, my improved construction operates safely and in the minimum of time in reversing the propeller.

It is to be noted that the provision of the sepa-` rate main clutch, which is the service clutch, permits the friction devices to be made small and light and by employing the automotive type of clutch, which is a spring-loaded dry-plate clutch, absolute freedom of the drive shaft from drag for reversing in the minimum of time is assured. At the same time overload protection for the propeller and propeller shaft is provided by such a clutch.

In theform `shown in Fig. 3, the clutch shaft I9' (which may be clutched to the engine crank shaftl by the usual friction clutch) extends into the gear housing 50 substantially horizontally and the engine may likewise be mounted horizontally as in automotive practice. The shaft lll in the present instance is mounted at the right hand end ofthe casing 50 in a double row ball bearing 5I which may be secured in place by the clutch housing (not shown), and at the left hand end of the housing in a similar ball bearing A52, thus providing adequate support for the shaft. A forward drive gear 53 preferably in the form of a herring-bone spiral gear is rotatably mounted as by means of a roller or needle bearing 54 on the shaft l0 or an enlarged boss or bearing sleeve 55 thereon. At the left-hand end of the casing 50 a reverse drive gear 56 similar to gear 53 is rotatably mounted on the shaft I0 in the same manner as gear 53, i. e., as by means of a roller or needle bearing 51. f The gear 53 meshes with a gear 5B carried by a stub shaft 59 which may be mounted at one end upon and 'supported radially and axially by a ball bearing 69 in the housing 50, and at the other end in a ball bearing 6I in a bore in the web or flange 62 in the housing. The left-hand end of the stub shaft 59 is provided with or carries a gear 63 which through an intermediate or idler gear 64 mounted in the housing is driven by the reverse drive gear 56. Thus the stub shaft 59 may be driven in forward direction by means of the forward drive gear 53 and in the reverse direction by means of the reverse drive gear 56 and idler gear 64.

'Ihe gears 53 and 56 at their adjacent ends carry friction and positive clutch means which may be in all respects similar in construction and operation to those carried by the quills I4 and 2| heretofore described and which need not be here again described. In Figs. 3, 4 and 5 the same reference characters have been applied to the clutch parts as those appearing on corresponding parts in Fig. 2. Thus', when the clutch shift fork 65 of Fig. 3 is moved towardthe right, the shaft I9' and gear 53 are first frictionally clutched to each other, after which the same may be positively clutched so as to drive the stub shaft 59 positively in forward direction.l By moving the clutch fork 65 toward the left, the reverse drive gear 56 and shaft i9 are first frictionally clutched to each other and thereafter positively clutchedso as to drive the stub shaft 59 in the reverse direction.

As illustrated in Fig. 3, the stub shaft 59 is arranged to dive the propeller shaft which in the drawings may be represented by a shaft 10 extending from the housing 59 and adapted to bc secured to or be a part of the propeller shaft. The shaft 19 extends at an angle to the housing 59 and at its inner end is provided-with a -toothed boss 1I splined thereon. Internally the gear 63 is provided with a similar toothed ring 12, and one or more balls or other coactlng devices 13 engage the teeth on the boss 11 and ring 12. The balls 13 and the coacting'parts 1|-712 constitute as a whole a constant velocity universal joint whereby rotation of the shaft v59 is transmitted to a propeller shaft 19 and at the same constant velocity as the shaft 59.

The shaft 19, extending from the housing 59 at an angle, is preferably mounted in an adapter housing 15 bolted or in the art.

otherwise secured to I the housing 59. The adapter housing is provided with a bore to receive a bearing such as a double row ball bearing 19 Yat the proper angle to support the shaft 19 at the desired angle to the horizontal. The bearing 16 is preferably of the double row type and takes both the. radial and thrust loads of the shaft 10.

As illustrated in Fig. 3, there is provided in a single housing a forward and reverse gear having both positive and friction clutch means, and by means of the universal joint within the housing the propeller shaft may be mounted at the desired angle while the gear housing is mounted horizontally. It should be no ted that in both forms of the invention disclosed, the forward and reverse gears operate with substantially equal `eiiciency in both forward and reverse. Thus, for

the axial twin screw installations, duplicate engines may be employed and one gear operated forwardly while the other is operated in reverse. Therefore, the premium usually paid for engines may be saved. It will furthermore be noted that the present combined reverse and reducing gear all in one housing saves considerable space and cost. The operation is rendered more trustworthy and there is less likelihood of partsgetting out of order when all are combined in one. Furthermore, by the provision of friction clutch reversing and pick-up means in both forward and reverse, relatively simple, cheap forms of vpositive clutches tical manner, a result not heretofore attainable.

In most cases it is desirable when actuating the forward and reverse gear clutches to throw out the main engine clutch between the engine and the gear. When shifting with the main engine clutch engaged, undue strain is placed upon the friction clutchdevices of the. gear and wear is likely to be rapid. ITherefore, in all cases, except at very slow speeds, the main engine clutch should bedisengaged before the shift is attempted.

I have devised improved means acting to first throw out the main engine clutch and hold the same in disengaged position until the forward vor reverse gear clutch has been actuated. One form of my improved means for facilitating shifting and which is applicable to those forms of the invention shown in Figs. l to 5, is illustrated in Figs. 6 and '1. In Figs. 6 and '1, 90 indicates the engine crank shaft carrying the fly wheel 9|. Friction disk clutch members 82--83 are located on opposite sides of the friction clutch disk 94. The clutch disk 84 is carried on the stub shaft 85 corresponding in all substantial respects with the shafts vIIl--Ill' heretofore described. Ring 96 is movable in a direction to separate the friction disks therefrom and from ily wheel 9| by means of a plurality of pins 91 and levers 99 in the usual manner and as will be understood. The levers 99 are shifted through a clutch bearing 99 and sleeve 99 which is itself shifted by means of a clutch lever 9|. 'I'he main engine clutch is engaged uponv a release of lever 9| by means of springs 92, all as is now understood 'I'he forward and reverse gear is substantially the same as heretofore described. In the form shown in Figs. 6 and 7, however, thev forward driving pinion is indicated at 93 vwhile the reverse gear pinion is indicated at 94 and drives through an idler gear 95 to the reverse gear 96. The forward drive pinion 93 drives direct to the forward drive gear 91, which gears, as will be understood,

are connected to the drive shaft 99 for the propelmay be employed in a pracright' and left-hand f shift sleeve 99 is actuated by a fork |00 which,

in the present instance, is provided with an up-V standing arm which is U-shaped as indicated at |0| to lit and be guided by and on an angular bar |02 extending outwardly into the main clutch housing where, through the adjustable screw |03, it is engageable with the clutch shift lever 9|. 'I'he opposite end of the angular bar |02 is forked,

as indicated at |03', to engage over the shaft |0| which is operable by a manual handle |05 employed for shifting gears.

I have provided means actuated by the shift lever |05 for throwing out the main engine clutch prior to shifting of the gears. In the form shown, the shaft |04 is provided with a xedly mounted arm |06 movable therewith and which at the end is provided with a cam surface |01 to engage the roller |08 on the angular bar |02. Thus, when the lever |05 is shifted toward the left, the cam` surface |01 acting through the roller |08 shifts the bar |02 toward the right so as to throw out the main engine clutch. The cam surface is provided with a depression |09 to ride on the roller and position the same centrally when the gears are in neutral position. The cam surface |01 extends at opposite sides of the depression |09 so that when the lever |05 is shifted in either direction from the neutral position, the bar |`02 will be permitted to move toward the left and the main engine clutch engaged by means of springs 92. 'I'he arm |05 and the shift fork |00 are interconnected and in the form shown I provide a slotted arm or extension ||0 on the shift fork and the arm |06'is provided with a roller l|| to engage within the slot of the arm ||0. 'I'he slot vof the arm l0 is of such formation that when the lever l|05 is shifted from its full forward clutched position toward the left, the first action of the arm |06 is to act through the cam surface |01 and roll |08 to disengage the main engine clutch. During this first disengaging movement, the roller moves in that part of the slot H0 which is concentric with the shaft |04 and no movement is transmitted to the clutch shift sleeve 99. When the main engine clutch has been disengaged, further movement of the fever |05 causes the roll to engage in an intermediate part of the slot l0 so as to first disengage the positive clutch and subsequently the friction clutch of the multiple clutch heretofore described. When the depression |09 is in engagement with the roll |08, the clutch shift sleeve and clutches are in neutral position andthe main engine clutch is disengaged. Further movement of the lever |05 toward the left will cause the roll engaging in an upper part of the slot ||0 to move the clutch shift sleeve 99 toward the right so as to engage the friction clutch of the reverse gear and still further movement causes the engagement of the positive reverse gear clutch, all before the main engine clutch is permitted to engage. Further movement then of the lever |05 toward the left permits left-hand movement of and reverse gear clutches due to4 thefact that allthe friction device has to do is` to pickup from either the forward or reverse gear element (being rotated by the propeller shaft), the relatively light stub shaft l5 upon which such gear element is carried, and the main engine clutch disk 04. The main engine clutch disk 04 is relatively light so that each friction device very quickly .and

readily picks up the few light parts and puts them in rotation in the opposite direction at the absorbed by the main engine clutch which has suiicient capacity for that purpose.

An additional advantage in employing the automotive type of clutch is that it is self-adjusting and hence reliable in action, which is -not true of the clutches of the reverse gear most commonly used in practice.

I have thus provided a very simple means for facilitating gear shifting in that a, single gear shift lever lon different parts of its movement in gear shifting direction first disengages the main engine clutch and holds the same disengaged before any shifting of the forward and reverse gear clutch either frictional or positive can take place.

. After the friction and positive clutches have been engaged, and only then', can the main engine clutch be engaged. v

While the invention has been described in considerable detail, it is to be understood that various changes and modifications may be made and that certain features may be employed without others all within the scope of the invention as defined in the appended claims.

I claim:

1. In a marine power transmission for driving the propeller of a boat in forward and reverse directions, constant mesh gearing, a double-actn ing tooth clutch associated therewith for reversing the propeller when turning, said clutch comprising shiftable teeth and forward and reverse teeth selectively engaged thereby and so connected to said gearing that when said shiftable teeth are being shifted from forward to reverse engagement to reverse the rotating propeller, the rotation of the propeller causes the reverse teeth and said shiftable teeth to be driven in opposed rotation, a friction pick-up device operable in rerelieving said friction pick-up device and said clutch teeth of strain during Ysuch shifting including a friction `service clutch, and means for holding said service clutch disengaged during,A v

such shifting and for re-engaging it after completion of shifting to initiate and effect reverse turning of the propeller through said service clutch and said tooth clutch.

2. In a marine power transmission for driving the propeller of a boat in forward and reverse directions, constant mesh gearing, including forward and reverse reduction gear means, a double acting tooth clutch associated therewith for reversing the propeller when'turning, said clutch comprising shiftableteeth and forward and reverse teeth selectively engaged thereby and so connected to said gearing that when said shiftable teeth are being shifted from forward to reverse engagement to reverse the rotating propeller, the rotation of the propeller causes the reverse teeth to be overdriven in opposed rotation relative to said shiftable teeth, a friction pick-up device operable in response to the shifting of said shiftable teeth to overcome such opposed rotation and to bring the shiftable teeth and reverse teeth into rotation in the same direction at approximately equal speeds prior to engagement thereof, for effecting such engagement Without clashing irrespective of the speed of rotation of the propeller, and means for relieving said friction pick-up device and said clutch teeth' of strain during such shifting including a friction service clutch, and means vfor holding said service clutch disengaged during such shifting and for re-engaging it after completion of shifting to initiate and effect reverse turning of the propeller through said service clutch and said tooth clutch. i

3. In a marine power transmissionv for driving the propeller of a boat in forward and reverse directions, constant mesh gearing. a double-acting tooth clutch ,associated therewith 4for reversing the propeller when turning, said clutch comprising shiftable teeth and forward and reverse teeth selectively engaged thereby and so connected to said gearing that when said shiftable teeth are being shifted from forward to reverse engagement to reverse the rotating propeller, the rotation of the propeller causes the reverse teeth and said shiftable teeth to be rotated in opposite directions,. a friction pick-up device operable in response to the shifting of said shiftable teeth to overcome such opposed rotation and to bring the shiftable teeth and re- '40 verse teeth into rotation in the same direction at approximately equal speeds prior to engage-v ment thereof, for effecting such engagement without clashing irrespective of the speed of rotation ofthe propeller, means for relieving said friction pick-up device and said clutch teeth of strain during vsuch shifting including a friction service clutch, and means' for vholding said service clutch disengaged during such vshifting and for :"e-engaging it after completion =of shifting to initiate and effect reverse turning of the propeller through said service clutch and said tooth clutch, and a single control lever adapted to 0p- -erate said shiftable teeth, said friction pick-up devices and said service clutch.l

` 4. In a power transmission, a shaft, constant meshi reverse'drive gearing, a double acting posv itive tooth clutch comprising sets of -teeth adapted respectively to provide -connections to said shaft for forward or reverse driving-'forward and reverse friction pick-up devices adapted respectively to overcome opposed rotation of the teethA of each set andA to bring therotation of said teeth into approximate synchronism to permit engagement thereof without clashing, a-friction service clutch, and means for disengaging said service clutch to relieve saidI friction pick-up devices of strain upon shifting said positive tooth clutch to disengage one set of teeth and engage the other set of teeth and for -re-engaging said service clutch after completion of` said shifting of said positive tooth clutchto initiate and effect forward or reverse driving through said service 'clutch and said positive tooth clutch.

5. In a power transmission, a'shaft, constant mesh forward and reverse drive gearing. a-double acting positive tooth clutch comprising sets of teeth adapted respectively to provide connections to said shaft for` forward or reverse driving', forward and'reverse friction pick-up devices adapted respectively to overcome opposed rotation of the teeth of each set and to bring the rotation of said teeth into approximate synchronism to permit engagement, thereof without clashing, a' friction service clutch, and means for dsengaging said service clutch to relieve said friction pick-up'devices of strain upon shifting said positive tooth clutch to'disengage one set of teeth and to engage the other set of teeth yand for re-engaging said service clutch after completion of said shifting of said positive tooth clutch to initiate and effect forward or reverse driving through said service clutch and said postive tooth clutch comprising sets of teeth adapted .respectively to provide connections to said shaft for forward or reverse driving, forward and reverse friction pick-up devices adapted respectively to overcome opposed rotation of the teeth of each set and to bring the rotation of said teeth into approximate synchronism to permit engagement thereof without clashing, re-

leasable connecting means between said friction pick-up devices and said positive tooth clutch lfor delaying engagement of the `teeth of either set until opposedl rotation of said teeth is overcome and said teeth are rotating approximately in synchronism, a friction service clutch, and means for disengaging said service clutch to relieve said friction pick-up devices of strain upon shifting said positive tooth clutch to disengage one set of teeth and engage the other set 'of teeth and for re-engaging saidservice clutch after completion of said shifting of said positive tooth clutch to initiate and effect forward or reverse driving through said service clutch and said positive tooth clutch.

7'. In a power transmission, a. shaft, constant .mesh reverse drive gearing, a double-acting positive tooth clutch comprising sets of teeth adapted to provide connections to said shaft for forand to consecutively operate one of the friction pick-up devices, to engage the other set of teeth of said positive tooth clutch and nally to engage said servlce clutch for initiating and effecting either forward or reverse driving through said service clutch and said positive tooth clutch.

DONALD H. MONTGOMERY.

-tive tooth clutch to disengage oneiset of teeth 

